From dd1a935ed4050e1f0540223c48e9d9de3e144bf3 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 13 Sep 2011 16:49:10 +1000
Subject: [PATCH] Add subtration operation for points

---
 point.cpp | 5 +++++
 point.hpp | 1 +
 2 files changed, 6 insertions(+)

diff --git a/point.cpp b/point.cpp
index d83c9e14..b302ab96 100644
--- a/point.cpp
+++ b/point.cpp
@@ -59,6 +59,11 @@ point::operator+= (const point &rhs) {
 }
 
 
+point
+point::operator- (const point &rhs) const
+    { return point (x - rhs.x, y - rhs.y); }
+
+
 std::ostream&
 operator<< (std::ostream &os, const point &p) {
     os << "point(" << p.x << ", " << p.y << ", " << p.z << ")";
diff --git a/point.hpp b/point.hpp
index 67ea8b53..04ef61e7 100644
--- a/point.hpp
+++ b/point.hpp
@@ -33,6 +33,7 @@ namespace util {
         double manhattan (const point &) const;
 
         point& operator+= (const point&);
+        point  operator-  (const point&) const;
     };
 }